Scientists working at the space agency’s Jet Propulsion Lab, in California, are investigating the Earth’s wobble – or “polar motion’.

The Earth drifts and tilts ever so slightly on its axis because it is not a perfect sphere and doesn’t spin smoothly.

Now NASA says it has identified three key reasons why the planet moves in this way.

The first factor is glacial rebound, which scientists used to think was solely responsible for the wobble.

(Image: GETTY)

This rebound occurs when glaciers cover a large area, causing the surface of the planet to be compressed and bulge at the edge of the ice.

As glaciers melt the bulging changes and this redistributes the Earth's mass. Although the last glacial period ended 26,000 years ago the planet is still slowly changing shape.

The second reason is called "mantle convection”, in which the shifting of large rocks in the Earth’s core cause a wobble.

But the third and final influence, a rapidly warming environment thanks to climate change, for which humans are partially to blame.

The melting of the ice caps in Greenland has meant that 7,500 gigatons of ice was transferred into the ocean.

This has changed the distribution of weight and may have contributed to the wobble.

Eric Ivins, from JPL said "There is a geometrical effect that if you have a mass that is 45 degrees from the North Pole - which Greenland is - or from the South Pole (like Patagonian glaciers), it will have a bigger impact on shifting Earth's spin axis than a mass that is right near the Pole.”

You can see an interactive demonstration of the Earth’s wobble on NASA’s Polar Motion Simulator.